The present invention is drawn to pre-filled syringes and, more particularly, a discoid and elastic valve to produce a hermetic closure inside a pre-filled syringe which keeps the liquid content to be injected totally isolated, in order to prohibit the liquid from coming in contact with the needle or the external air. More specifically, a discoid and elastic valve is designed to block up the neck of the syringe from inside, in order to close the communication between the syringe""s internal main body, where the liquid is, and the needle which is connected in the syringe neck through its plugging cone.
The characteristic feature of known pre-filled syringes is that they have a cylindrical and hollow main body, with a front section where a communication neck with the injection needle is formed, while inside is a manually movable plunger which extends outward from the back of the main body which is open. All of these known syringes have an inner chamber formed inside the main body, constituting the temporary location of the liquid to be injected. This inner chamber is defined by the cylindrical wall of the main body, the above mentioned front neck where the needle and the active head of the manually movable plunger.
Argentine Patent No. 250,277 discloses a syringe which supports a very special valve plug whose function is to keep the liquid isolated inside of syringe body thus avoiding contact with the needle until the injection is performed. Thus, during the placement of the needle and coupling it to the plugging cone or syringe neck and withdrawal of the protecting sheath to perform the injection, the liquid is kept isolated inside the main body of the syringe, ensuring that these coupling and uncoupling actions do not cause some unwanted loss or spilling. The plug is specially designed to be placed in the neck occluding the same from the outlet mouth. It is important to point out that the plug of the mentioned Patent No. 250,277 is specially designed for the mouth of the syringe neck that faces the injection needle. Due to its special shape the same releases the liquid only when hydraulic pressure is produced from the plunger towards the syringe. This pressure partially removes the plug and the liquid flows.
The discoid valve of the present invention is also specially designed to isolate the liquid contained in a pre-filled syringe, avoiding its contact with the needle; however, it clearly differs from the cited prior art due to the fact that it works operatively in a different way.
The valve of the present invention is located inside the main body to perform the closing action at the inlet of the communication duct that defines the neck of the syringe. The valve of the present invention has a coaxial stub that fits in the inner part of the syringe neck closing it and forming a hermetic chamber that contains the liquid to be injected. This new arrangement ensures the impossibility of unwanted losses of liquid, with the additional feature that, being inside the syringe body, every manipulation that may be performed during the couplings and uncoupling of the injection needle, as well as its respective protection sheath, may never lead to leakage. Likewise, if the plunger is accidentally pushed in an injection action, the seal will be greater.
The new functional concept incorporated with the invented valve is that it is necessary the plunger move in a direction opposite to the injection direction in order to provide a free flow of the liquid to the needle. When moved as described above, the stub is removed from its sealing location and the valve withdraws itself thereby allowing the passage of liquid.
This action, which is not possible with other plugs, is very important in that the action necessary for the release of the closing stub, allows one to know that the needle is inserted correctly. As it is known, if the needle is inserted in a vein, the sucking action, causes the entrance of blood in the syringe which is desirable and necessary evidence of proper location.
Accordingly, it is the principle object of the present invention to provide a discoid and elastic valve to produce a hermetic closure inside pre-filled syringes suitable to be placed inside the syringe body, occluding the communication passage towards the injection needle fitted on the neck of these, which consists in a single body that comprises a cylindrical stub that projects itself perpendicularly from a flat and elastic central portion (base) of circular shape, which includes a series of holes neatly distributed therein and is limited by a perimetrical ring that fits tightly on the inner face or the cylindrical wall of the syringe.
Another characteristic of the value is that the cylindrical stub projects from the center of a flat and elastic base and the holes are neatly distributed in a circular manner on the flat base. It should also be noted that the perimetrical ring is circumferential and thicker than the elastic base (central portion).